It was Dr Nobuyuki Tanaka, the Japanese taxonomist, who created a set of working measurements for Canna rhizomes, and he used them to help him categorize the wild species, resulting in his Taxonomic revision of the family Cannaceae in the New World and Asia in 2001. This revision was the start of bringing order to the chaos we had previously experienced in naming of our Canna species. The categories defined by Tanaka are:
- thick, up to 3 cm in diameter
- thick, up to 7 cm in diameter
- long and thin
- tuber-like groups
- no rhizomes
To the first four specified by Tanaka, we have added the fifth category. At Claines Canna we have grown C. paniculata that did not have any rhizomatic growth, and Dale McDonnell, in Australia, has had this same experience, having inherited an old Foliage Group specimen that displays the same characteristic.
We have used this classification for some years now, and we cannot find any fault with it.